CareerCup

Non-Functional
1. Check file size
2. Check file type
3. acrobat reader is installed?
Functional-
1. Check if other pdf is opening
2. Check mime type of pdf
3. Check what error showing while opening the file

Check the file extension, it needs to be .pdf for it be read in any pdf reader software
Check the file permissions
Check the file is not 0B size
To drill down whether its a file problem or software problem
Try to open the file with a different software, or just
Open a different pdf file using the same software and see if it works
Act on the error returned when you opened the file and it failed

Here are some debugging points which i will follow
1. Check if you have install any pdf reader.
2. Check if you are able to open that pdf reader.
3. Close pdf reader and again try to open the file.
4. Update the pdf reader.
5. Try to open the pdf file in any other pdf reader.
6. Check if the file is of valid format.
7. Check if the file is downloaded completely.
8. Try to open that pdf file in any other system.
9. Check the system RAM.
10. Check the memory consumption of system by the application.
11. Close other running application of the system.
12. Restart the system and again try to open the application.
13. Reinstall the pdf reader application.
14. Check if the application is blocked by any third party software etc.
15. Check the compatibility of application with OS.
16. Try to open some other pdf file in pdf reader to cross check.
17. Check if the pdf file requires password to open.
18. Check the error message if it is throwing some error while opening that pdf file.
19. Check if the pdf reader is running any other pdf file.
20. Check the file size.
21. Check the file extension.
22. Check the file permissions.
23. Restore the system to previous working conditions.

Initially i will confirm whether it have some content with it, or not by its size.
Make sure of the error by open it in nitro pdf and adobe
If same prob occurs means then try to convert it to word file or rich text format or even a image file.
Else go with OCR converter, there you can definitely get the solution.